Blepharitis is the most common cause of visits to the ophthalmologist's office outside of refractive error. We hypothesize that meibomian gland dysfunction, with alterations in meibomian lipid composition, plays a major role in blepharitis and in dry eye through evaporation effects. Understanding these changes will aid in developing therapies and designing lipid substitutes. Dry eye is more frequent in women, and is also one of the most common presenting complaints in ophthalmology. In our previous grant we developed methods for accurately measuring tear flow, osmolarity, evaporation, and meibomian gland function. We found that almost all tear film functions decline with age. We also found with age a greater loss of lacrimal capacity in women than men. We hypothesize there is significant hormonal influence on tear function, in addition to the decline in function with age. The overall purpose of this grant is to proceed with this work on the tear film, blepharitis, and dry eye. Specific Aim: l) Assess the influence of sex hormones on tear function in humans. 1a) Study the effects of normal and abnormal androgen levels on tear function. 1b) Evaluate the effects of normal and abnormal estrogen levels on tear function. 1c) Evaluate the effects of abnormal prolactin levels on tear function. Specific Aim: 2) Determine the correlation between changes in lipid composition and the resulting clinical and physiologic parameters of tear film function. Evaluate the changes in composition of meibomian lipid which occur with 2a) age, 2b) specific meibomian gland disease states, 2c) altered evaporative rate. 2d) Evaluate patients with Rosacea and seborrheic dermatitis to determine the effects of these dermatologic diseases on the tear film. 2e) Refine our classification of blepharitis and tear function using 2a-d data. 2f) Evaluate tear function following the addition of various lipids to the tear film layer. Specific Aim: 3 correlated tear film function with the confocal appearance of the tear film lipid surface in normals, disease states and contact lens use. 3a) Refine tandem scanning confocal microscopy of the lipid layer 3b) correlate altered functions of the tear film found in disease states with the confocal microscopic appearance 3c) Use confocal microscopy and evaporation measurements to investigate the tear film changes which occur with contact lenses.